Mixed-type multicentric Castleman's disease developing during a 17-year follow-up of sarcoidosis.

Multicentric Castleman's Disease (MCD) is a systemic disease characterized by generalized lymphadenopathy and the proliferation of plasma cells. The development of MCD in a patient with preexisting sarcoidosis has not been previously reported. We herein describe a case of MCD developing in a 78-year-old woman with a 17-year history of sarcoidosis. The patient's serum interleukin-6 (IL-6) levels were only slightly elevated; however, the IL-6 levels in the fluid of both pleural effusion and ascites were markedly elevated. The administration of steroid-pulse therapy and prednisolone was ineffective in treating the MCD, although treatment with tocilizumab proved highly effective.